In many situations, certain waste materials must be removed from waste solutions before the solution is allowed to flow into public sewer systems. Typically, the waste solutions are created by a processing facility located in a mall or other building connected to the public sewer system and arranged between the processing facility and the sewer system.
The present invention is of particular significance when used to remove metals from waste solutions destined to flow into a public sewer system. A common example would be a photograph processing facility employing a developing process using silver. Other examples would be fixers and other solutions for photographic, X-ray, and lithographic processes and the tailings from electrolytic plating processes. In all of these situations, environmental laws may require the removal of certain metals from the waste solution. And in some situations, such as when silver is used in a photographic process, the metal to be removed may have value.
Accordingly, a number of systems and methods have been developed for removing metal ions such as silver from a waste solution. The present invention relates to such removal systems that are connected between a drain in which the waste solution is disposed and the public sewer system. These systems typically comprise a two-stage filtration system using steel wool as the reaction media. Such removal systems typically employ two interchangeable containers containing steel wool. The waste solution is caused to flow first through one of containers and then through the other of the containers. Usually, the first container in series is removed and returned for processing, the second container in the series is placed first in the series, and a new container is placed second in the series. The returned containers are typically processed at a central location remote from the source of the waste solution to recover the precipitated metal.
Available metal ion removal systems that employ two stage treatment may be too complex for certain users. Such systems require at least a minimum level of expertise, and the potential exists for error in installation and operation of these systems. In addition, the use of two separate containers increases the possibility for leaks.
The need thus exists for an improved system for the removal of metal ions from solutions that is simpler to operate than known metal removal systems.